Piston



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M 0 vla. H. ,W

W. A. ROTH v PISTON Filed June 4, 1943 Aug.- 27, 1946.

Patented Aug. 27, 1946 I T ED vST.15II`IE`S 0F 1l-.C E

-rls'roN- William Alltoth, St. Paul, 'Minn. .Application-June 4, 1946,.;seria11Nm 469,611.2-

1 `Claim.

Myyinve'n'tionfrelatescoran-'improvement infpisrtonsffor internal .combustion engines of :thefour- -cycle type. lA primary object of my invention .is to remove, during the exhaustxstroke, practically the entire exhaustzgasesthat arepordinarily .trapped vin the clearance space of the present type-:of internal combustion'fengines.

yAnother object :of .primary .importance is fito provide a means fory increasing the amount of fuel and air mixture d-rawn finto the l*cylinders during the `intake stroke, without 'the use -of supercharger means, when this is Afound to be :.desirable.

The foregoing objects provide a piston for internal combustiony engines to 'increase efficiency.,

power, and a :great :saving'in fuel during the operation of v.the Vinternal combustion engine. The increased efficiency and power obtained by using my piston in 'internal `combustion engines tends to provide an;engine ofsrnaller -Weight for the .same power than an internal combustion engine .using the ordinary type iof^piston.

.A further feature resides in providing aninternal combustion engine with lower intake and compression temperatures, #thereby permitting the use of loweroctane fue'lfor "the same` compression 'ratio, yor 'higher compression ratio `for the same octanefrating.

My piston "is applicable fto airplane motors, wherein Ibelieve it A,willdevel'op greater efciency with a decrease in engine weigh'tfor thepower developed bythe engine usingfmyfp'istons. These pistons may be used "to .adVan-tagein automobile, Diesel, and other engines :of the four-cycletype, where perfomance as defined hereinis desirable.

The details and further' features of my @pist-on will' be more fully hereinafter'set forth.

In the drawings rforming Ya part of :my specication:

Fig. `V1 .illustrates :a ydiagranmiatic `cross-section of an internal combustion fengine, showing. my pistonr therein.

Fig. .12 isa cross-section of-an alternativer form of myy piston.

Fig. 3is asection onfthe lined-#L3 Lof=Fig. `1.

Fig; 4 'is a section cn'thel line f4-4 of .Fi-g. "1;

`My piston A may '.beused in anyftypey ofxf'ourcycle internal combustion "engine, fand isfiprovided with a zhead portion ISU whichfmay be formed-integral .with theskirt Il as `illustrated l-in Fig. l'.

The head I0 is formed with a dependingcylindricalmsleeve I 2 which extends into the piston iin parallel relation to the wall of :thexskirtV "Id tto provide a recess 1.63-1-between-'the wall of: the'iskiizt fI'I ,-andxthefwa'lli.oithe;5s1eeve;l2..

.In the -lower endfof the skirt -Hr Igprovide :a sleeve `I 4 whichfis 'threaded inside 'the-lower rend of .the fsleeve l|-.I .fa-nd :is adapted .to Vbe fixed by the pins I5 to the sleeve II of the piston.y"1-lhe inner end-of the sleeve :I4: is in the form of a cylindrical walllf which is parallel toV the fwall :Il fof the skirt :of thepiston and thereby Eprevides -amecess IFI: whichis Y.complementalin size andshape to the vannular :recess 1'3 inside ,of the head .ofthe-piston `A. f

The "cylindrical" sleeve' lI`2` andi the sleeve portion I4 :have the vsame-axis and extendin the same cylindrical plane; being spacedrapartvand adaptedI to kprovide 6a, :bearing for tlaevlends of the-Wrist pinisleeve 6B. 1Tire-wrist zpin fIc is mounted centrally between the .ends in the sleeve B kinfamy lsuitable manner and 'is adapted "to support "the `upper end :of vvthe connectingfrod C.

vThe wrist' pin 'sleeve'. B is vadalcited to :slide `in the .pist'on .-Aso that the skirts 2-0v and 25| on .each end of the :sleevesoperate in a .close-fitting manner in '.-therecesses 'lf3-and IFI, respectively. 'An oil: lm Awhiclfrv lnbricates "the piston .A `alsolirbri- Cates .the `sleeve B, and an air cushion is `-built upfiril the :recesses -:I 3i and .1I .'I.v :to V 'cushion'tl'1e operation fof Ttlaepiston A `with `thex'sleeve B as "the piston' :reciprocates in the engine cylinder A.22.

Ilprovid'ea series sof 'large holes 213' `to ladmit air lubricating v'oil to 'the piston and Lsleeve Binthe recesses ISI and ='I"I' respectively; I also provide aseri'esse'f `smallholfesll at the bottom,

and a similar Vseries :of` :small .holes V2l! yslightly abovethe bottom, foffeach recess I3 and I1, re spectively, Ito: permit air and -oil to gradually 'escape fromthese recesses vin the l:reciprccation 'of the sleeve B within the` piston. `The size and number of .the series of holes 23 and `2&1 to 'be proportioned soy as to :admit the vair freely into the recesses il3and '121,:and'to restrict` the escape of .fair the recesses .so that an air `cushion may ibeform'ed'- tovpreventrs'hock .between 'the `piston Auand the ends :of 'itlne sleeve :Bfwhilefinrapid motion with respect. to reach. other.

In operation my piston A will :reciprocate'iin the 'cylinder '22 in uthe Ioperation `*of the internal combustion engine; @The imovementof' the-piston A willbe different with respect .to the sleeveB and the cylinder :ZZzduri-r-Lgv each `fstrolaefof afourcycle engine.

At the end-vof .the power stroke-and the beginning foff the exhaustfstro'ke theeupper face ,2:5 Aof the `sleeve B will .be-.in-v contact wit-h -the yface .26 at the bottom vof the;` recess |f3, the lower part `2| of. the .sleevefB Wllbe Withdrawnfronr therecessv I1. the recess I1 being lled with air or gases from the crank end side of the piston. During the exhaust stroke the piston A will stay in this position with respect to the sleeve B until a point, somewhat more than one-half the length of the motion of the sleeve B is reached, when the sleeve B will begin to slow down, the piston i A being atits highest rate of speed at this point will tend to continue at this highest rate of speed, and thus proceed towards the head o-f the cylinder at aA faster rate than the sleeve B.

Simultaneously, while this action of the piston A is taking place, the air and gases in the recess I1 are being compressed, rst lightly, to permit Y the piston A to move freely, and then compressed, vmore strongly as the compressed gases'iail'to` escape through the holes 24 as fast as theyare being compressed, thus checking the speed of the piston A, an-d bringing it to rest, at the end of its forward motion, at the same time that the sleeve` B vcomes lto the end of its forward motion, and

the sleeve B where the-inertia force is reversed,V

building uperapidly to a valuehigher than it had at thebeginning of the stroke.V With the gases in the recess I 1 building up a pressure rapidly: enoughtocounteract theinertia force ofthel piston A, it is' brought'to `the end of its forward motion and into contact with the sleeve B with-` out shock, and when timed with the closing of the exhaust valve, which should close at the time the piston comes into near but not actual contact, and close at aboutthe same rate as the piston 'A movesv near the end of the stroke, thusv expelling practically all of the exhaust gases above piston head I0. Somewhat better results may be had when used withsleeve-valve engines.

The second series of holes 24 somewhat above withdrawn from the recess I3, this recess filling with air and gases from the crank side.Y of the piston-the piston A holding this position with respect to the sleeve B up to a point somewhat less than one-half the length of the stroke of the K the sleeve 2l'being withdrawn from the recess I1 whilethe sleeve 20 enters the recess I3, compressing the air and gases in the recess I3 and similarly as in the exhaust stroke, bringing the piston' A to rest without shock, with the face 25 in contact with vthe face2I.v The piston A comes tothe end of its motion at the same time as the sleeve 'B comes'to the end of its motion.V That is, the piston A and the sleeve B come to Vrest simultaneously, the piston A moving further than the sleeve B bythe length of the clearance space, which equals the length of theV motion of the sleeve B inthe recesses VI3 and I1.

The timing of the openingof the suction valve must be such that as the piston v'A leaves the I cylinder head, thel valve follows the piston vA the bottom of the recess I1 and I3 are 7for the purpose of allowing the compressed air andY gases of its motion, but after thisseries of holes is closed by the ends of the sleeves B passing them,

Vthe remaining holes 24 at the bottom of the re-r cesses will let the compressed gases out still more slowly, thusinsuring that no metal to metal shock results. Suiicient lubricating oil will enter the holes 23 and 24 during the operation of the piston -to lubricate the bearing surfaces and to form a ,seal therebetween to prevent the escape of the compressed air and gases from the recesses except through the holes 24. Any excess of oil tending toaccumulate in the recesses I3 and I1 will be forced out through the holes 24 to prevent water-hammer. l

` In order to more completely expell the entire exhaust gases during the exhaust stroke, it is` necessary to modify the shape of the combustion chamber when my piston is in use.

As the piston A reaches the end of its motion at the end of the exhaust stroke which then becomes the beginning of the suction stroke, the piston remains in the position it then has, that is, with'thebottom edge 2 1 of the sleeve 2| in contact vwith the face V28, the upper sleeve 20 being closely withoutrbeing in contact with it. 'This' octane rating since the danger of preignition or,

detonation is absent. Also., the fuel and air mixture being free from exhaust Vgases will burn.

more quicklyand' completely, thus higher eiliciency andgreaterlp'ower are assured. When less power is:desired,v part throttle operation will result in the same high efficiency inthe absence of the blanketing effect of the vexhaust gases.

At Athe beginning of the compression stroke, the piston A will remain in the position it has at the end of the suction stroke; that is, the face 26 will be in contact with-the face 25 and will remain in this position throughout thev compres-Y sion stroke as well 'as the-power stroke. During the compression strokel the inertia forces will act, or tend to act, identically the same as during the exhaust stroke, but here during the compression stroke the fuel and air mixture being com-1 pressed, the total pressure on the entire area'of the head of the pistonA will rise rto a higher Vvalue during all parts of the stroke thanthe inertia forces, and thus keep the piston A in the same position with respect to the sleeve By during :the entire compression stroke as it had at the beginning of the compression' stroke, the force on the piston due to the compression of the fuel 'and air charge, acting counter to the Ainertia force during the last part of the piston stroke, the piston A with the sleeve'B acting together as'a solid piston. Y f

During the power stroke, after the gases have been ignited, the compressed gas 'and air mixture will rise to a still` higher pressure,l thus holding the piston A inthe sameirelatin' tothe sleeve B that it had at the beginning of the compression stroke, during the compression stroke, and will remain so to the end of the power stroke, the same as a solid piston.

At the end of the power stroke the cycle will be repeated as above described.

I claim:

In a gas engine having a cylinder and piston rod, a piston with outer Walls engaging the inner Walls of the cylinder, a cylindrical sleeve connected with the piston rod and reciprocable within the piston for operating the same and having annular end walls of substantial width, cylindrical cups connected with the piston end walls and shaped and positioned to form annular chambers for receiving the annular ends of said sleeve, and two rings of apertures through the Walls of both said cups, the apertures of the outer ring in each case being of large diameter to admit crank case gas and oil freely into said annular chamber, and the inner ring apertures in each case being very much smaller and being positioned close to the inner ends of the annular chambers to permit only sloW discharge therefrom for effecting a strong cushioning action in the transmission of the force of reciprocation of the sleeve in both directions to the piston.

` WILLIAM A. ROTH. 

